A toothed rubber belt is a transmission belt sometimes called as timing belt.
Different from general V-belts, the toothed belt itself has a tooth form and transmits a power by directly interlocking with toothed wheels.
Accordingly, since the toothed rubber belt is required to have mechanical characteristics capable of enduring stress directly applied to the tooth, the product is required to endure more severe conditions than general rubber belts.
A toothed rubber belt has been used for a power transmission system such as automobiles, motorcycles, bicycles, etc., as a substitution for conventional metal chains.
Hitherto, as a toothed rubber belt for automobiles, a toothed rubber belt using chloroprene rubber as the rubber material has been widely utilized.
However, with the recent increase of the temperature of the engine room of an automobile and the increase of the using life thereof accompanied by maintenance-free properties, a toothed rubber belt using a rubber material more excellent in heat resistance and durability than those of chloroprene rubber has been desired.
On the other hand, chlorosulfonated polyethylene is a rubber material which is better than chloroprene rubber in heat resistance, weather resistance, and ozone resistance and, hence, is a preferred material for improving the heat resistance and durability of a toothed rubber belt.
However, since chlorosulfonated polyethylene is greatly inferior in cold resistance to chloroprene rubber, it is sometimes difficult to clear the cold resistance required for toothed rubber belts.
Accordingly, a rubber material for toothed rubber belts capable of enduring the severe conditions required for meeting both heat resistance and cold resistance as in the case of automobiles has been demanded.